41 
common oyster, and the large fresh-water muscle. 
entirely with those already before the public, either in this 
country, or in France, I have only to observe, that although 
others may have laboured the subject for a greater length of 
time, none, I am sure, have brought more diligence to the 
enquiry, or have more frequently revised the observations 
that were first made, with a view to correct any errors that 
were detected. With respect to the drawings by which the 
facts are illustrated, I can answer for their fidehty, should any 
voucher be necessary beyond the author’s name. 
On the mode of breeding in the Oyster. 
The structure of the ovaria is so little developed, that it is 
difficult to discover these organs ; and in the first instance, it 
requires the aid of the microscope for that purpose, even in 
the breeding season. 
In this country, where the beds are not allowed to be 
disturbed during the season in which oysters spawn, we 
labour under a considerable disadvantage in the prosecution 
of this enquiry ; and I am indebted to my friend Mr. Cope¬ 
land Hutchinson, who procured for me the opportunity of 
examining some oysters weekly, during the period they are 
prohibited from being sold in the public market, taken from 
a private bed near Sheerness, 
The situation of the two ovaria, for I consider them to be 
double, as in fishes, is immediately within the membranes that 
line the two shells, having the liver placed between them ; 
they consist of a membrane, whose use is not to be ascertained 
till the ova become visible attached by pedicles, and hanging 
from it. The structure of the liver resembles so closely 
that of the ovarium, while containing ova, as only to be 
MDCccxxvir. G 
